programs running on 18 pin project boards having either adc or input requirements will only work correctly when download cable is still connected. laptop rs232 provides neg 9v standby. created neg 9v circuit to provide this voltage to the resistor serial input on project board. while this neg 9v is present programs work fine. can anyone figure out what is happening?
serial input voltage problems
- Thread starter ewug89
- Start date
Although I cannot find the earlier post using Search, didn't we do this subject already, a few days ago ?
When you say "will only work correctly when download cable is still connected", can you explain exactly how it doesn't work, what exactly doesn't work, when the download cable is connected.
Does everything other than ADC work when the download cable is unplugged ? Have you done any additional testing to check it's not your software partly causing the problem ?
As someone ( dippy ? ) suggested; is it a case that it doesn't actually work with the download cable connected. Inserting the download cable will alter ADC readings unless the Enhanced Download circuit is used.
It sounds to me that you either have the 10K/22K download resistors wired incorrectly or missing, a Reset pull-up missing, or the way you handle ADC readings makes it appear not to work when the download cable is unplugged.
There is no need to connect -9V to the serial input to make a PICAXE work as it should.
When you say "will only work correctly when download cable is still connected", can you explain exactly how it doesn't work, what exactly doesn't work, when the download cable is connected.
Does everything other than ADC work when the download cable is unplugged ? Have you done any additional testing to check it's not your software partly causing the problem ?
As someone ( dippy ? ) suggested; is it a case that it doesn't actually work with the download cable connected. Inserting the download cable will alter ADC readings unless the Enhanced Download circuit is used.
It sounds to me that you either have the 10K/22K download resistors wired incorrectly or missing, a Reset pull-up missing, or the way you handle ADC readings makes it appear not to work when the download cable is unplugged.
There is no need to connect -9V to the serial input to make a PICAXE work as it should.
BeanieBots
Moderator
This was answered when you asked the same question in the "fried 18X thread".
You have either built the download circuit incorrectly, you are using a potential divider device without the other half of the divider or you are using a high source impedance on the ADC input.
If it is the later, the problem is actually the other way around, readings are correct WITHOUT the download cable and wrong with it plugged in.
Post a circuit diagram (tinypic or similar)and details of you expect compared to what you get and we will be able to advise on corrective action. There is absolutely no need whatsover to require a negative voltage on serin. It is the opposite, a negative voltage on serin causes the ADC to malfunction.
You have either built the download circuit incorrectly, you are using a potential divider device without the other half of the divider or you are using a high source impedance on the ADC input.
If it is the later, the problem is actually the other way around, readings are correct WITHOUT the download cable and wrong with it plugged in.
Post a circuit diagram (tinypic or similar)and details of you expect compared to what you get and we will be able to advise on corrective action. There is absolutely no need whatsover to require a negative voltage on serin. It is the opposite, a negative voltage on serin causes the ADC to malfunction.